Japanese Architecture

Measures in Japanese Architecture Measures used in Japanese architecture originally came from the Asian continent, going on to help Japanese people create their own lifestyle, using Japanese wisdom and customs.

Also used in China, the Korean Peninsula, and Taiwan

Japan's historic measure of length, called the kanejaku, or square, originated in China. It was designated as Japan's official measure in 701 by the Taiho Code. This unit of length comprises the shaku, the sun, and the ken; 10 sun equal 1 shaku and 6 shaku equal 1 ken. These units have been used for centuries in Korea and Taiwan as well as in China. Even today they are used from time to time, together with the modern metric system. The kanejaku has therefore been a common architectural measure in Asian countries around the Sea of Japan and the East China Sea for more than a thousand years. In the Japanese kanejaku system, one shaku is about 30.303 cm, and the smallest unit, the bu, is about 3 mm. Because of Japan's humid climate, expansion and contraction of wood is a serious problem when building structures. Therefore, these relatively bigger units are considered better suited to Japanese architecture.

Tatami, the original modular home furnishing

The term "module" in architecture refers to a standard unit of measure used when determining the size of building members or calculating space. It was after World War II that this concept came into worldwide use, and it is now indispensable in industry. In Japan, a similar concept was already in use in the Medieval Period. This standardized architectural unit was the tatami. Named after a unique rectangular floor covering, it measures 6 shaku and 3 sun (about 190 cm) in length and 3 shaku and 1.5 sun (about 95 cm) in width for the type used in the Kansai region, popularly called kyo-ma. In reality, the size varies somewhat from place to place, for example, when compared to those used in the Kanto region and in collective housing. But generally speaking, even children understand the size of a room when someone says it is a 4.5-tatami or 6-tatami room. The number of tatami mats used for a room then determines the spacing between columns, resulting in standardization of fixtures, such as sliding doors and paper screens. Japan's tatami is therefore the forerunner of the module concept.

Dimensions based on comfortable living

Step-up rail

When local carpenters build a house, there are several measures they use almost habitually. For example, it is rather difficult to step up onto the step-up rail, the place one first steps after taking off shoes, when it is 8 sun (about 24 cm) or higher. To make ceilings appear less oppressive, they are built with a camber equal to one bu for each tatami mat in the room. Eaves and lean-to roofs are 0.5 ken (about 90 cm) wide and the veranda 3 shaku and 5 sun to 4 shaku (about 105 to 120 cm) wide so as to prevent rain from blowing in and to let in cool breezes and allow the winter sun to shine into the room. These dimensions have been developed through centuries of carpentry and have also been proven scientifically effective. This kind of know-how is not simply technical; it also demonstrates carpenters' thoughtfulness toward residents.

Traditional weights and measures and modern life

	The traditional system of weights and measures is called shakkan-ho, from shaku, a unit of length, and kan, a unit of weight. This system had been widely used in Japanese life for centuries, affecting the formation of Japan's traditional culture. It was in 1891 under the modern Meiji Government that the metric system was officially introduced. The shakkan-ho was repeatedly modified to cope with internationalization and technical innovation and was finally banned in 1966 for use in contracts and for certification. Despite being banned, it is still used at worksites involving traditional wooden architecture or for handicrafts where the tools are still based on the old measures. It is also the basis for paper sizes for books and bills. Thus the ancient system of measure remains alive, coexisting with the metric system.

Shakkan-ho			Metric system	Imperial system
ken	shaku	sun	m	yd.	ft.
1	6	60	1.8	1.8	6